IMPS Progress in Board and Paper Technology March 2007

Transcription

1 IMPS th International Munich Paper Symposium Progress in Board and Paper Technology March 2007 R. Beltz, Emco GmbH, Leipzig and G. Meder, Mohn media Mohndruck GmbH, Gütersloh / Germany "The most critical paper characteristics for printability"

2 Complexity of printing 100 years ago Printing at 1904: N e person heads E n printer printing E //i// //i//! "Black art": Particularly on the activities of the printer and the typesetter this name is applied. To the Gautschen representatives of these professions " disciple the blacks' art ", may themselves call "black artist" or disciple "of Gutenberg". In a similar connection the concept "white art" which refers to the skills at the papermaking exists.

3 Complexity of printing today Printing 100 years later: Printing industry colour industry paper industry machinery manufacturer printer... And who steers what?

4 Cooperation Paper manufacturer printery Paper mill Finished product Complaint Raw material Printing House Print product Product specification + established examining norms Research, examination of print problems

5 What is the interest for the printer? Reproducible, sufficient regularity of the material (paper, ink, glue,...). Information about the product behaviour for the planning, Production preparation, process control The paper must run!!! ( Printability, Runability) However, the classic paper specification is not decisive for it!

6 IFRA report Runability Use requirements Properties of the paper Train demolitions (holes,) Fundamental properties Walking for the train Structure qualities Mechanical qualities Train stability Young's modulus ( Register) Fold formation Chemical qualities Runability Thickness changing + 5% at 40?(800 E 805) + yields 64 mm+1280 mm Train and rolls qualities eveness of this one Expression Connection between paper qualities and use requirements with regard to Runability (IFRA report) FAN OUT DWs, KWs Separating ability unpicker for rope perforation Fold break Electrostatics Further processing safety

7 IFRA report Printability Qualities of the paper Fundamental properties Structure qualities Use requirements Fillers fray Deposits Coating Deposits Assigned Pressure problems Pulling up Negative Piling Blinding Mechanical qualities Chemical qualities Printability Colour acceptance Water acceptance Colour need Positive Piling Ghosting Vanishing Dots Visual qualities Pressure sharpness Gleichmässigkeit of this one Expression Mottling Connection between paper qualities and use qualities with regard to Printability (followed IFRA report) Colour drying water drying White-washes or Opacity? Cockling Verb lure Greasing

8 Problem analysis prints Our problem analysis approach Ink Pressure process gives relevant properties of every component! Print technology Paper Print press relevant properties of: Print press technology / machine Colour Paper The paper is object of the refining, that is reference point for every pressure process analysis! What are print press process relevant properties?

9 Influence matrix printing Surface energy Roughness/topography Material type Side/hardness Composition f (time) Viscosity Surface tension f (t) Rubber cloth Piece of paper water Pressure Time Process conditions: Contact time on rollers Temperature/atmospheric humidity geometric order Discount behaviour/angle Effects in the Nip Coloured printing inks Emulgat Composition f (time) Viscosity/Tack/G ', G; Dehnvisko Emulsion quality (droplet size) Surface tension Entmischneigung/Entmischkinetik colloidal stability Emulsifying inclination DF/WW/kinetic Way blow behaviour Compressibility f (P, humidity, fibre type,) Elasticity, flexibility Plastizität/Deformierbarkeit Z strength Humidity Grammatur, volume 2-Seitigkeit Topography Base paper Substratum (Coating) Surface energy Kapillarität/pore volume distribution absolute pore volume Roughness/topography Area of the pressure point Complex interplay of all parameters or there are A-factors for printing relevant parameter?

10 Time conditions in the printing press 5 mm?~ 10 sec µ m?10-10 sec -5-6 Example: Grid distance 70 Lpc, 40% global coverage Matrix dot diameter: 102 µ m yields 5 mm Pressure Nip RW Grid- Point ~ 100 µ m Dryer/KWS Superstructure/f old 10 m/s 2 m 2 m 2 m ~ 15 m ~ 19 m V =?10 m/s 0.2 sec 0.2 sec 0.2 sec 1.5 sec 2 sec ~ 4 sec? V = 15 m/s 0.13 sec 0.13 sec sec 1 sec 1.3 sec ~ 2.6 sec? Damp water must having disappeared in the paper surface, next before paper Reached Nip place has! > 1 sec Dwell time in the dryer

11 Temporal classification of the pressure problems VD G NP PP Capillary transport V. Liquid into pores Steam diffusion into pores Matrix dot moving the Nip? Trapping matrix dot meets the next Ink Mottling Cockling Web offset Water shipment to the fibres Drying Pressure point deserts publications 1-4 Dublieren Fold PRAC TISE Drying problems Abschmierproblems Bar forklift Palettierer Greases Verb curls, stick of products U = 620 mm V = 15 m/s Matrix dot: 100 mm Nip = 5 mm Publication distance = 2 m Paper length DW 1 fold = 40 m Store Smell formation sec 1 min. 1 H ~ 1 day 11 days lg t sec Short time Middle time Long time

12 Visual densities for coloured printing inks with a different colour layer thickness 1 MT colour layer thickness: Black D = 1.8 Cyan D = 1.5 D = 1.4 magenta Yellow D = 1.3 s Standard (paper class 2): Black D = 1.75 Cyan D = 1.45 D = 1.4 magenta Yellow D = 1.25 (Kipphan, manual of the print media)

13 Dependence of the matrix dot diameter R of density step x and grid distance RW 2 R RW = (grid value z.b 60s grids, RW = 60) FR LRW LRW = grid distance x TW = density step = (e.g. 40% density step x = 40) % density step meant: 40 2 FR L RW R [μm] F R 2 R x 100 L 2 RW x RW R 1 RW x x = 20 RW

14 Matrix dot diameter Grid diameters: /1000 mm

15 Size conditions in the pressure 1 µm water layer or colour layer 5 Coating Z Z µm 5 µm 60 g/m2 Paper 60 µm 1 µm Water, colour layer 15 µm 5

16 Where is the colour?

17 Where the colour is, where the water? Coloured micrograph of paper fibres A scanning electron micrograph of fluid inside The partially saturated zone of paper. It shows The pore ares unfilled and that fluid is moving through film flow, need The paper primarily ace via The bulk filling of pore (ace hectare traditionally been thought to be, The Case). credit: photo by Ray Roberts

18 Absorption dynamics into coated paper (Schölkopf, Gane, The moment ink contacts of The surface..) The balance between Spreitung, penetration/absorption influences the process Surface energy of the phases involved (celebration liquid, gaseous) determines contact angles and with that the wetting A geometric order of the different interfaces checks the motion of the gas/liquid interface meniscus () Surface roughness has influence External pressure Chemical inequality The dynamic absorption behaviour of Fluiden to a porous medium determines this one printability of painted papers in the context of the way blow behaviour. Parameters are pore structure, size distribution the pores: (preferred pathway river) capillarity and permeability.

19 t (ms) Contact paper/top-hat, Dwell time t (L1) w2 w1 L Verweilzeit der Rasterpunkte im Gebiet L FO 21 FO 35 / 36 FO 27 / 29 / 31 L FO 33 FO 25 / 26 / 37 / 38 / 39 / 40 / 41 L FO 23 FO 43 w3 2 0 Ex/h in tsd FO43 FO23 FO39 FO 25 / 26 FO 37 / 38 FO 40 / 41 FO 33 FO 27 / 29 / 31 FO 36 FO 35 FO 21

20 DV / TWZ Example pressure problem Vanishing Dot Test II - FO29 unteres DW ' 110' 111' 112' 113' 114' 115' 118' 119' 120' 121' 122' 123' 124' 125' 126' 127' 128' 129' DV 1,82 1,51 1,61 1,65 1,67 1,65 1,67 1,6 1,62 1,68 1,71 1,71 1,69 1,75 1,75 1,81 1,8 80% 40% DV 1,4 1,3 1,37 1,39 1,4 1,36 1,38 1,31 1,35 1,37 1,37 1,43 1,43 1,42 1,4 1,41 1,4 80% 40% DV 1,62 1,64 1,65 1,63 1,64 1,66 1,65 1,65 1,63 1,61 1,61 1,63 1,63 1,65 1,64 1,65 1,66 1,65 80% 40% DV 1,74 1,7 1,74 1,73 1,75 1,72 1,75 1,68 1,69 1,68 1,7 1,71 1,72 1,72 1,7 1,72 1,72 1,72 80% 40%

21 Example printing problem Ghosting

22 Example pressure problem Vanishing Dot, Ghosting Colour (pigment, binder, additives) Water, damp means Surface tension ph Elektr. conductivity Harden etc. Temp. Viscosity, toughness Water photo Fluctuation into consistency Colour additions (paste, thinner,..) Rotation Top-hat order Top-hat diameter Separating acceleration Farb, damp plant Roller cover Plate Negative/positive Grid Preservative Water photo Rubber cloth Type Topography Compressibility Spring resistance Quick release Paper Type, line Grammatur Resistances Sucking ability, porosity, Perm. Seitigkeit ph Process Train speed Train tension Farb, water leadership Temp., dampness Subject (front U. back)

23 Paper specification and printing phenomena There is no simple correlation between a pressure problem on the one hand and an effect or a parameter of the paper specification on the other hand. It is important to analyse the different printing problems and phenomena for the printer lead her to different working mechanisms. It is important to know the potential for a printing problem (e.g. Ghosting, verb curls etc.). It depends on different factors and conditions, whether and as the printing problem also really appears strongly.

24 "The journey is the reward. Topography Behaviour with water, oil (capillarity, sucking ability) Young's modulus (dampness) strength Tack measuring Identification values paper, standard (thickness, V, type,)? Colour consumption Train thriller Pressure problems Printability Runability Print quality

25 Problem analysis printing Our problem analysis approach Pressure process gives relevant properties of every component! Print process relevant properties of: Print technology / machine Ink Paper The paper is object of the production, the paper has to be in the focus for every print process analysis! What are print process relevant properties?

26 The hidden properties of the paper 1. Surface topography 2. Compressibility/strength 3. Capillarity The nature of a paper Paper fibres are hygroscopic, i.e. they react in the environment to humidity, temperature and therefore also to air pressure until a balance state adapts. These events are dynamically and directly connected to a change of physical qualities of the fibres and the fibre structure. 4. Water absorbency (surface tension of the fibre wall) 5. Dimension (thickness, length MD, breadth of CD) 6. Modulus of elasticity (E-Modul) 7. Grammage and stiffness as a function of the water content. The nature of the paper determines its process properties!

27 Process properties of printing papers to Beltz and Meder The major properties of the paper for the print press process are: 1. Topography (ink assignment, amount of ink, colour impression, colour construction) 2. Compressibility in the print gap (ink assignment, ink stand) 3. Capillarity (ink absorbency, ink anchorage, ink drying, ink stand) 4. Water absorbency (surface tension of the paper and the fibre wall) 5. Dimension stability and strength (opposite water and temperature) 6. Elasticity and its change in dampness and heat (E-Modul) 7. Absolute water content condition of the paper (balance dampness). The properties 1-6 are dependent on the water content of the paper! One can measure all important printing process relevant properties and one get numerically values for each property!

28 Process property Topography 1 st property: topography 2 nd measuring principle: direct measuring of the property Stripe light projection determines millions some height information with an evaluable resolution of 0.1 µm in the point grid 1600 x 1200 (1,92 ) to an area within 6 seconds. Sensors are used for printing papers by 100 mm² or 400 mm² with measuring areas. 3 rd measurement result parameter Calculating out judging algorithms which are mathematically dominated and motivated: roughness measure and values according to DIN EN ISO 4488 and 4487, roughness in ± µm surface volume in cm 3 /m 2 scaredness index according to Dr. Praast Kriti's heights and depths with number and area, decision value in µm eligible for office. 4 th significance for the printing process Ink assignment, ink consumption, colour impression, stood liability, colour construction Comparison of the topography before and after the pressure uncovers the effect of the printing process for the topography, e.g. offset Heatset, decoration pressure. Print phenomena: Mottling, Missing Dots, barns.

29 Process property Compressibility 1 st quality: compressibility 2 nd measuring principle: indirect measuring of the property Stripe light projection determines millions some height information with an evaluable resolution of 0.1 µ m in the point grid 1600 x 1200 (1,92 ) to a line area within 6 seconds. The paper is pressed at the measuring with a line pressure corresponding to the printing process against a visually transparent plate. 3 rd measurement result parameters to one defined pressure calculating out judging algorithms which are mathematically dominated and motivated: roughness measure and values according to DIN EN ISO 4488 and roughness ± µm surface volume in cm³/m 2 scaredness index according to Dr. Praast Kriti's heights and depths with number and area, decision value in µm eligible for office. 4th significance for the pressure process Ink assignment, ink consumption, colour impression, ink stand, ink construction Compare it with and without under pressure repetitions and dampness steps is possible for topography provide information about the process understanding Print phenomenon: Mottling, Missing Dots, Ghosting.

30 Process property Capillarity 1 st property: Capillarity 2 nd measuring principle: indirect measuring of the property Ultrasound transmission measuring emcodpm after dynamic contact of a paper page with n-heptan. 3 rd measurement result parameter emco7 (td) from page 1 and emco7 (td) from page 2 in the print process relevant time duration D. 4 th significance for the printing process Ink absorbency Ink drying Ink anchorage Ink construction Colour impression, pressure gleam, colour intensity Print speed area Sideness (differences between side 1 and side 2) Print phenomena: verb curls, stick together, Dublieren, Ghosting, grease, put down board like stiffening.

31 Process property Water absorbency 1 st property: Water absorbency 2 nd measuring principle: indirect regulation of the quality Ultrasound transmission measuring emcodpm after dynamic contact of a paper page with distilled water. 3 rd measurement result parameter emco1 (td) to of emco7 (td) from page 1 and from page 2 in the pressure process relevant time domain D. Measuring is also possible with damp means and other liquids. 4 th significance for the pressure process Dynamics of the damp middle photo Print speed area Seitigkeit (differences between page 1 and page 2) Water sensitiveness of the surface Whether capillary penetration or fibre absorption conclusions about this are Pressure phenomena: greasing, put down, Dublieren, verb curls, stick together.

32 Process property Dimension stability 1 st property: dimension change at wetting and drying 2 nd measuring principle: direct measuring of the property Dynamic measuring of the length change into CD and MD under water or humidity influence and drying. The change of the water content in the fibres lets itself be seen by expansion and shrinking. There are two different measuring principles which measure the change by load cell or optical by image analysing. 3 rd measurement result parameter Dimension change in % extended over a time domain which establishes the change. Time domain (milliseconds) is possible and required the dissolution on a print process relevant. 4 th significance for the pressure process and the further processing Wrinkle, Fan out potential, Flatness, waviness in multilayer products, waviness in the printed area, Long time stability of print products, Loss of gloss, grow over of edges.

33 Bahnspannung [dan/m] Process property Dampness dependent modulus of elasticity 1 st property: dampness dependent modulus of elasticity 2 nd measuring principle: indirect regulation according to the method of Beltz & bellringer Under defined dampness conditions the Young's moduli are determined. With a second method the dynamics of the dampness photo of the paper is determined. 3 rd measurement result parameter Dynamischer E-Modul-Verlauf 400 emco Methode Papier C Papier A Papier D Papier B ,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8 2 Einwirkzeit [s] 4 th significance for the pressure process Provision of the specification values for Bahnspannungs, colour register and cut register regulations. These can do one fully automatic on the paper and its dampness condition secure abgstimmte process control.

34 Process property Water content dependent paper condition 1 st property: water content at balance dampness 2 nd measuring principles and method: indirect regulation with a method. Regulation of the environment climate of the paper, at least the temperature and the relative humidity of the air. Determination of the water content in the paper automates with a NIR method or with a hand-held test equipment "emcodelphin". A measuring judging comparison in a time domain shows, whether the paper is to the environment in the balance. 3 rd measurement result parameter temperature of the surrounding air in degrees Celsius relative dampness of the surrounding air in % rh weight per cent water in the paper with a reproducibility of 0.1% whether the paper was yes no statement about this in the balance. 4 th significance for the pressure process Condition determination of the paper, Transferability and interpolation of the parameters of the paper specification (this is only valid for a norm climate) on the current climate in the pressure hall, Supervision of dewpoint and critical climate conditions.

35 What is won for printer? The paper is in the focus! Knowledge of the print process relevant properties of paper (numerically): 1 st choice (purchase) of the suitable paper 2 nd arrangement (order, machine, ink, paper) 3 rd consideration in the prepress (plate) 4 th fine tuning of the ink (future) 5 th machine presetting (regulation ranges) at consideration of the climate 6 th cause analysis in the problematic case and knowledge profit at every phenomenon!

36 Quality management+efficiency The measurement concept connects PAPER MANUFACTURER Online measuring (Safeguard the regularity) Paper Lab laboratory Paper Lab + database Database all material and process relevant data of a paper and his NIR reference spectrum PAPER CONVERTER NIR terminal Paper reconnaissance and assessment of the condition Material data for converting processing and process control

37 NIR terminal emcoppa Print Integrated double climate measuring (temperature and humidity) in the room and at the paper 3D SLP Scanner NIR DOMAS modules Topography Roughness Surface-Volume Scaredness Structures etc. Paper identification Contents substances quantitative Water content Cooperation between partners manufacturer and printers!